CHAPTER 1. MEMORIES ARE MADE OF THIS
THE BRAIN
OUR MEMORY BANK
EXPLICIT MEMORY
Hippocampus
The hippocampus is where episodic
memories are formed and indexed
for later access. Episodic memories
are autobiographical memories
from specific events in our lives, like
the coffee we had with a friend last
week.
Neocortex
The neocortex is a sheet of tissue
that forms the outer surface of
the brain. Over time, information
from certain memories that
are temporarily stored in the
hippocampus can be transferred to
the neocortex as general knowledge
– things like knowing that coffee
provides a pick-me-up. Researchers
think this transfer from hippocampus
to neocortex happens as we sleep.
Amygdala
The amygdala attaches emotional
significance to memories. This is
particularly important because
strong emotional memories (e.g.
those associated with shame, joy,
love or grief) are difficult to forget.
The permanence of these memories
suggests that interactions between
the amygdala, hippocampus and
WORKING MEMORY
Prefrontal cortex
The prefrontal cortex (PFC) is
the part of the neocortex that
sits at the very front of the brain.
It is the most recent addition
to the mammalian brain, and is
involved in many complex cognitive
functions. Human neuroimaging
studies (using magnetic resonance
imaging - MRI – machines) show
that when people perform tasks
requiring them to hold information
in their short-term memory, such
as the location of a flash of light,
the PFC becomes active. There
also seems to be a functional
separation between left and right
sides of the PFC: the left is more
involved in verbal working memory
while the right is more active in
spatial working memory, such as
remembering where the flash of
light occurred.
neocortex are crucial in determining
the ‘stability’ of a memory – that is,
how effectively it is retained
over time.
IMPLICIT MEMORY
Basal ganglia and cerebellum
The basal ganglia are structures
lying deep within the brain and are
involved in a wide range of processes
such as emotion, reward processing,
habit formation, movement and
learning. They are particularly
involved in co-ordinating sequences
of motor activity, as would be
needed when playing a musical
instrument, dancing or playing
basketball. The basal ganglia are the
regions most affected by Parkinson’s
disease. This is evident in the
impaired movements of Parkinson’s
patients.
The cerebellum, a separate
structure located at the rear base of
the brain, is most important in fine
motor control, the type that allows
us to use chopsticks or press that
piano key a fraction more softly. A
well-studied example of cerebellar
motor learning is the vestibulo-
ocular reflex, which lets us maintain
our gaze on a location as we rotate
our heads.
MEDICAL ILLUSTRATION: LEVENT EFE